Voller revealed last week he was in London "to negotiate" a summer switch for Schurrle, with the midfielder expected to sign a five-year contract at Stamford Bridge while Kevin De Bruyne heads in the opposite direction on loan - though Leverkusen are thought to be eyeing a permanent switch.

"The transfer of Schurrle is a question of the total package. There are some more items and De Bruyne is one of them," Voller said on TV show Sky90.

"[De Bruyne is] a top alternative and can play a similar position like Andre. If a good player leaves we´ve got to sign another good, or even better, player."

Despite Chelsea reportedly being close to seal a deal for Schurrle, Voller feels the youngster would be better served with more regular first-team football as he looks to break into the Germany squad ahead of World Cup 2014.

"Next year is the World Cup and then he wants to be a starter for Germany," Voller added. "He has the potential."